The U.S. Pat. No. 4,433,494 describes a method for obtaining an item of clothing or accessory, in particular a ski boot, closely fitted to part of the human body, by the thermo-forming of an inner lining of thermo-formable material, by means of an electrical heating element incorporated in said lining, this lining and the part of the human body in question being placed mutually under pressure after having heated the lining to its thermo-forming temperature by means of the heating element. The heating element used is obtained by the chemical attack of a polyester support coated with a layer of aluminium, in order to form a meander able to constitute a heating element of sufficient length. However, when in use, it has been found that if this heating element is heated several times, the polyester hardens and causes fractures of the aluminium, i.e. cutting of the heating element which thus becomes unusable. In any case, thin aluminium does not behave well under stress and fractures or tears rapidly when it is subjected to repeated bending stress, as is the case for example in an inner lining of a ski boot. Henceforth it is no longer possible to proceed with new thermo-forming, for example in order to refit a ski boot to the feet of the user, nor to use the heating element as a means for heating the item of clothing, for example a boot or glove.